Electron discharge device



May 14, 1935. c E, FAY

ELECTRON DISCHARGE DEVICE Filed May 12, 1935 INVENTOR C. 5. FA)

A TTORNEV Patented May 14, 1935 "UN TED: STA

" "nrno'rnon DISCHARGE DEVICE virrational;

Cliiiord E. my; South Orange, N.';J.,, assignor to Bell TelephoneLaboratories, Incorporated, New Kerk; N.'Y., a corporation of;New YorkApplication May- 1-2; 1933; Serial 1%; 670,692

foclaims potato-27.5 W V 1 This invention relates toelectron' dischargede-;

vices :and more particularly to such devices adapted forthe generationof ultra-high frequency' oscillations and-commonly known in the 5- artasBarkhausen' oscillators.

3 andthereby to increase-the'powercapacity of the device; ii T 1Another, object the operating characteristics Barkhausenoscillators. -Inone embodiment of this invention, an elec -v trondischargedevicecomprises aicylindrical electrode, a cathode and anoutput or'grid' elecand" efficiency of trode within-the cylindricalelectrode andextendingsbeyond the ends thereon; 1 a

The cathode comprises-a linearinlamentsupported at its ends and disposedcoaxiallywithin the cylindrical electrode; The output electrodecomprises a pair of spaced .tubularmembers positioned, beyond the endsofithet cylindrical electrode and a plurality' of parallel; linear wiresextending between the tubular membersiand disposed in a cylindricalboundarycoaxial with-the cathode and the cylindrical electrode. v :Inaccordance with a feature of this invention, the parameters of theelectrodesare correlated so that azrelativelyhighioperating efliciencyis ob- In accordance with'another feature" of this in vention, heatradiating members are associated with output electrode in orderto'dissipate the heat therefrom; In one form the members may comprisemetallic discs of relatively large area; mounted on the tubular membersof the output electrode assembly. y 1 p I In accordance withaiurtlierfeature of this in# vention; a plurality of imperforatetubular.memebers are mounted on the cathode, and surround the portionsthereofextending beyond the ends of the cylindrical electrode. Thesefmembersserve to confine th'e electron flow to adesired path and prevent theflow of electrons to the; tubularmembars in the output electrodeassemblyQ; j y r: The invention and the, various features thereofunderstood more clearly and! fully from capacity of devices of this'typeis lim- I w 'electrode;and"

or this inventicn'is ts improve wires :34.

' traction of the rods 20 the following detailed description withreference to the accompanying drawing in which: 1 4 Fig.1 is aperspective view of'an electron-;dis-; charge device illustrative ofthis-vinventiong with I portions-of the enclosmgvesseland ot'the elec-.trode structures brokenaway to show details of construction moreclearly; V Fig. 2 is an enlarged end Viewof'the electrode assemblyshowing the relative disposition of? the g cathode and the outputelectrode, filament-leads 10 and-the heat radiating membersfor theoutput;

in cross-section showing and output electrode ras rFigL3 is a side viewdetails of the cathode sembli'es. a y, Us

Referring? to the drawing, the device shownisi of the-type adapted forthe generation-'oi"ultra'-' I high: frequency oscillationsand commonlyknown as a Barkhaus'en oscillator. It comprises evacuatedenclosingvessel l0 havinga reentrant "20 stem H which. terminates in a"press I2."A pair ofibentlor substantially inverted Leshap'ed wires t3 are embeddedat 'one'end in the press l2 and 1 have secured thereto a pair; ofparallel metallic rods or uprights l4. A single linear fi1amentl5 25. oftantalum, tungstenror' other material having good electroniemitti'ngcharacteristics, is secured at its ends to'the rods or uprights andserves as the cathode of "the device. 'The" heating cur-' rent for. the.cathode may be supplied through leading-in conductors .Hi connected tothe 'A bent wire i1 is embedded at one end inthe press 12 and at theother endin 'an'insulating bead IS, the wire' i! being disposed; in aplaneat, substantially rightfangles to the plane of the wires l3. Ametallic-ribbon i9 is secured at one end to a rod Zillembedded in-theinsulating bead l8, and at the other end to another rod 2l"sealed in theend of .the enclosing vessel 10' as shown at;22; The'ribbon l9is'p'referably flexible a'nd bowed to allow longitudinal expansion andcon and 2| with temperature variations.- r J 1. I A cylindricalelectrode 23'ha'ving 'aflange 24 is supported from rigid L-shaped wires25 se? curedyas by welding, to the rod 20 and .to the flange 24 and areinforcing rod or wire 4| on the'flange. The electrode 23 may be ofsheet molybdenum, the surfaces of which areroughened by carborundumblasting to increase the heat radiation therefrom, and. isdisposed-about and spaced coaxially with respect :to the filement [5. li A bent wire PATENT- 26' is embedded'at one endin the press l3 andcarries an insulating bead 21. A bowed flexible metallic ribbon 28,similar to the ribbon I9 is connected between a rod 29 embedded in theinsulating bead 2'! and a rod 30 sealed in the enclosing vessel It asshown at 3!. A U-shaped wire support 32 is secured to the rod 29 and isrigidly held in position by braces or rods 33 secured'thereto and .tothe rod 29.

An output or grid electrode assembly is carried by the support 32 andcomprises a pair of cylindrical metallic collars 34 connected to thearms of the support 32 by short rigid wires 35,

only one of which is shown in Fig. 1. The'collars 34 encircle the endsof the filament lfiand have secured thereto a plurality -01 equallyspaced parallel wires 38 whichmay be of tungsten and are disposedparallel to the filament l5 and arranged in a cylindrical boundarycoaxial with the filament. Y

Thisconstruction provides a substantially noninductive electrode andinasmuch as the wires 36 are symmetrical at all points with respect tothe filament IS a uniform field between the filament and the wires isobtained with a resultant uniformityof electronic action. Furthermore,this construction facilitates the conduction of heat from the centerportion of the wires 36 to the ends-thereof and thereby enables thedissipation ofthe heat by, radiation.

'Indevices'oi the type described, the electrode 23 is usuallyoperated atzero potential, or at a slightly negative potential with respect tothefilament l5'and the grid or output electrode is very'smallsurface areaand is spaced veryrclose to the filament. For example, in a devicecapable of producing oscillations of a wave length of the order ofltlcentimeters', the gridor output electrode may have an inner diameterof 0.156 inch, the gridwires being'0.010 inch in diameter, and thefilament may be 0.008 inch in diameter.

During the operationof the device, the grid be-; comes heated and thepower output of the device is therefore limitedby the temperatures whichthe grid' electrode can safely withstand. In

order to increasethe power capacity of the de-,

vice, means are provided, in accordance with a feature of thisinvention, to dissipate the heat fram the grid electrode. Forthispurpose, a pair of vanes or annular discs 31 of relatively large,

area, and of a material having good heat'radiatingchara'cteristics, forexample, molybdenum or nickel roughened by carborundum blasting, are

disposed adjacent the ends of the grid wires 36 and are thermallycoupled thereto. 'The disc 31 may be disposed in contact with thecollars 34 and may be connected to the collars by a plurality of bentwires 38 of good thermal conductivity. In order to insure uniformoperating'charac teristics and a relatively high operating efliciency,the collars 34 are preferably disposed beyond the ends of the electrode,23. To substantially prevent the fiow of electrons'to the collars'a'ndthere by to confine the electrons emitted from the filament I5 to pathsembracing the wires 36 of the output electrode, the end portions of thefilament within the collars 34 may be surrounded by tubular sleeves 39of nickel or the like, secured to the uprights I4 by tabs 40.

The efficiency of devices'of the Barkhausen oscillator type is dependentto a material extent upon the relative diameters of the grid electrodeand the electrode 23." Particularly goodresults are obtained withdevices in which the diameters of the electrode 23 and of the output orgrid electrode are in the ratio of substantially 3.6 to 1. Variations ofplus or minus 10% in this ratio, that is, the ratios being betweenapproximately 3.2 to 1 and 4.0 to 1, have been found to be notparticularly detrimental.

Although a'specific embodiment ofthis invention has been shown anddescribed, it is to be understood, of course, that many modificationsmay be made therein without departing from the scope and spirit of thisinvention as defined in the appended claims.

What is claimed is:

1. An electrode assembly for electron discharge devices, comprising apair of spaced metallic cylindrical members, a plurality of wiresextending between and secured at their ends to said members, said wiresconstituting an electrode, metallic discs of relatively large areaadjacent said cylindrical members, and a plurality of members of highthermal conductivity connecting said cathode, and acylindricalelectro'de encircling said output electrode and disposedcoaxially therewith, the ratio of the diameters of said secondcylindrical electrode and said output electrodebeing between 3.2 to land 4.0 to 1.

3. A Barkhausen oscillator comprising a cathode, a cylindrical outputelectrode encircling said cathode, and a cylindrical'electrodeencircling said: output electrode and disposed coaxially therewith, theratio of the diameters of said second cylindrical electrode and saidoutput elec trode'being substantially 3.6 to l. V 4. A Barkhausenoscillator comprising a cathode, a cylindrical electrode encircling saidcathode and disposedcoaxially therewith, and an output electrodeintermediate said cathode and said cylindrical electrode including aplurality of parallel wires mounted in a boundary coaxial with saidcathode, the ratio of the diameters of said cylindrical electrode andsaid' boundary being substantially 3.6 to 1. V

5. An electron discharge device comprising an enclosing vessel having astem, a plurality of wires extending from said stem, a cathode mountedon said wires, a plurality of supporting members embedded in said stemat one end and anchored at the other end to said enclosing vessel atpoints remote from said stem, each of said supporting members having aflexible portion, an electrode carried by one of said members andencircling said cathode, and another'electrode carried by another ofsaid members encircling said first electrode and coaxially disposedtherewith.-

6. An electron discharge device comprising an enclosing vesselhaving astem, a plurality of supports extending from said stem, a filamentextending between two of said supports, a cylindrical electrode carriedby another of said supports, and encircling said filament, a pair oftubular members carried by another of said supports and encircling saidfilament, and an electrode extending between and secured to said tubularmembers.

'7. A Barkhausen oscillator comprising an enclosing vessel having astem, a cylindrical electrode supported from said stem, a linearfilament disposed coaxially within said electrode and having portionsextending beyond the ends thereof, sleeve members encircling saidportions, a support extending from said stem, a plurality of mounted ina cylindrical boundary coaxial with said filament.

8. An electron discharge device comprising an enclosing vessel having astem, a plurality of supports extending from said stem, a filamentextending between two of said supports, a cylindrical electrode carriedby another of said supports, a pair of spaced metallic cylindricalmembers carried by another of said supports, a plu rality of wiresextending between and secured at their ends to said members; said wiresconstituting an electrode, and metallic vanes of relatively large areamounted'on said members.

9. A Barkhausen oscillator comprising an en,-

closing vessel havinga stem, a cylindrical elec-' trode supported fromsaid stem, alinear filament disposed coaxially within said electrode andhaving portions extending beyond the, endsthereof, sleeve membersencircling said portions, a support extending from said stem, aplurality of tubular members carried by said support and encircling saidsleeve members, a plurality of f wires extending between and secured tosaid tubular members, said wires being disposed parallel to one anotherand to said filament and mounted in a cylindrical boundary coaxial'withsaid 7 filament, metallic discs of relatively large area adjacent saidtubular members, and a plurality 'of members, of highthermal'conductivity con-

